Some $1.5 trillion in mortgages will come due in the next two years, a potential time bomb as higher interest rates and spiraling office vacancies push down property values.

And because 70 percent of bank-held commercial mortgages sit on the balance sheets of regional and smaller lenders, a write-down in commercial loans could spell big trouble for the financial system and spill over into the larger economy just as the 2024 presidential campaign gets underway.